Formosa wrote:The Raven Guard had some pretty good stealth tech, turning the void shields inside out, stopping any kind of emissions escaping into space, making them near invisible, it would even likely make them invisible to the naked eye, since all radiation is blocked.

Thats new (or incredibly old in 40k's case). Have you got a source on that?

yeah of course dude, Ravens flight, Corax, soulforge, etc.

They are called Reflex shields if I remember correctly, remember that most astartes vessels are from the GC era, so id imagine this tech to be rare, but still there, a good example, salamanders still have pyroclasts in 40k, in the most recent 40k book for them, they also had thallax.